Electric-current interrupter.



K. TROSDAHL.

ELECTRIC CURRENT INTERRUPTER.

APPLICATION FILED MAY 9, 19w.

Patented. June 26,1917.

1O make and use the same,

UNITED STATES PATENT OFFICE,

KNU'I inosnann, or CHRISTIANIA, NORWAY.

To'aZZ whom it may concern;

Be it known that I, KNUT TROSDAHL, a subject of the King of Norway, residing at Christiania, in the Kingdom of Norway, have invented certain new and useful 1m .provements in. Electric-Current Inter .rupters; and I do hereby declare the-follow- U ing to be a fulLclear, of'the invention, such and exact description as will enable others skilled in the art to which it appertains to to the accompanying drawings, and to letvters or figuresof reference marked thereon,

which form a part of this specification.

' The present invention has for its object an electric current limiter of the periodical interruption type, in which the interruption of the electric current is effected by the expansion of a volume of air, heated by means of a resistance, through which the electric current passes. Theexpansion of the said volume of air acts to press an insulating fluid, such as oil 'into a channel, containing mercury and forming part of the current circuit. 'When oil is introduced in the said channel, the string of mercury is divided and the current interrupted On the drawing is shown a diagrammatical section through a form of the in- 'vention.

The apparatus comprises a vessel 1 of insulating material, such as porcelain, 'in the interior of which is located a W-shapd to such a channel 2, filled with mercury 3 height that the mercury forms a continual bathf through the W-shaped channel. i The side and middle members of the W-' shaped channel each open into closed chambersi, 5 and 6. In the middle hhamber 6 7 layer of oil 7.

the surface'of' the mercu y is covered by a The electric'current passes from Wire '8 through resistance wire 9 in the closed chamber 6 to contact wire 10, dipping nto.

the mercury at the bottom of chamber 4. From here it passes through the mercury inthe W-shaped channel and through contact wire 11 in: chamber 5 to wire 12 which is connected to lamps or other current consuming apparatus 13.

, adjustable resistance 14:;

reference being had i located in the said connectin dium, a ehannel I 1 current, located in Parallel to resistance wire 9 1s. shunted an ELECTRIC CURRENT INTERRUPTER.

' Patented June 26, 1917'.

Applicationfiled May 9, 1917. Serial no. 167,438,.

through resistance wire 9 will heat the air 1n chamber 6 to such an extent that its ex; pansion will press the'oil7 down into the middle .members 15, 16 of the W-shaped channel, separating the mercury as indicated in dotted lines on the drawing.

Hereby the current'is interrupted, andthe air in chamber 6 will be cooled and contract until the "strings of mercury in 15 and 16 are again reunited, cuit, whereupon the same operation is repeated until the consumption of current is limited. a The amount of current for which the apparatuswill start operating may be regulated by means of shunt resistance 14. Z

In order that the temperature outside the.

apparatus shall not affect its operation, the

sum of the volumes of chambers 4:, 5 must be equal to the volume ofchamber 6.

Although the layer of oil in the chamber 6 is an advantage in order to minimize the interruption spark .and prevent the oxidetion of the mercury, it is obvious that the may be dispensed with without interfering with the operation of the current interrupter, and this particularly is thecase if a non-oxidizing gas, such as nitrogen or the like is used in the chambers.

Claims:

1. In anelectric current interrupter three closed chambers'filled with a gaseous me dium, a channel connecting the lower ends of said chambers, a continuous body of mercury, forming part of the current circuit, channel, and'a resistance w1re, heated by t e electric current, located in the middle chamber, for the purpose of heating the gas in the same and eflect interruption of the current by expansion of the said gas, when the current consumption has reached a certain limit.

2. In an electric current interrupter three closed chambers filled with a gaseous meof said chambers, a continuous body of mercury, forming part of the current circuit, located in the said connecting channel, and a'r'esistance wire, heat'edby the electric the middle chamber, for the purpose of heating the gas in the same and effect interruption of the current by expansion of the said gas, when'the current consumption has reached a certain limit, the volume of said middle chamber being, equal to the sum of the volumes of the two closing the current cir+ connectingth'e lower ends located in the said connecting channel, a-

other chambers, for the purpose of making the apparatus independent of variations in the outside temperature. L

3. In an electric current interrupter three closed chambers filled with a gaseous medium, a channel connecting the lower ends of said chambers, a continuous body-of mercury, forming part of the current circuit,

resistance wire heated by the electric current, located iuthe middle chamber, for the purpose of heating the gas in the same. and

efiect interruption of the current by exand an adjustable resistance shunted on the circuit in parallel, to'the heating resistance *for the purpose of regulating the apparat-us. j

In testimony that I claim the foregoing as my invention, 1 have'signed. my name in presence of two subscribin witnesses.

- ,nosn' Witnesses:

C. FABBICIUS HANSEN,

C. P N. 

